Nonpolar light emitting diodes of m-plane ZnO on c-plane GaN with the Al2O3 interlayer

Nonpolar m-plane ZnO films are deposited on GaN (0002) with a 10 nm Al2O3 interlayer by atomic layer deposition. The growth direction of the ZnO films directly on GaN (0002) is [707¯4] (perpendicular to (101¯1) plane), whereas with the Al2O3 interlayer it changes into [101¯0]. With the Al2O3 interlayer, the m-plane ZnO films are presented and the leakage current of the heterojunctions dramatically reduces. The electroluminescence spectra of the n-ZnO/Al2O3/p-GaN heterojunctions are dominated by a blue emission under forward biases, whereas it is violet under reverse biases.